1. Field of the Invention
The invention relates to composite nonwoven fabrics suited for use as breathable roof lining.
2. Description of the Related Art
Moisture vapor permeable roof lining or roofing underlayment materials are intended to protect the interior of a building from the ingress or penetration of water or rain, while allowing moisture vapor to escape from within the building. As such, materials in this application need a high degree of liquid barrier and moisture vapor permeability.
EP Patent Number 880628 B discloses a moisture vapor permeable roofing underlayment comprising a meltblown layer sandwiched between two spunbond layers, optionally treated with hydrophobic additives. The meltblown layer is heat treated in order to make it more film-like. The patent discloses the use of polypropylene and polyurethane in the meltblown layer.
EP Patent Number 742305 B discloses a moisture vapor permeable composite fabric suitable for building construction uses, including roofing underlayment, in which a meltblown layer is sandwiched between two spunbond layers. The meltblown layer is compressed in order to reduce the pore size. Hydrophobic additives may be included in the layers.
It would be desirable to have a roof lining material with a high degree of liquid barrier and with good moisture vapor permeability that does not require special treatment of the meltblown layer to achieve a low pore size.